Sound-reproducing apparatus



June 17, 1930. H. J, MURRAY SOUND REPRODUCING APPARATUS Original Filed Sept. l5, 1921 2 ShetS-Sheet l afm d@ llllll l Il llllmll J u u v u IIVIVVVIPIL 1 OOOGOOOOGG n yJune 17, 1930. J, MURRAY 1,765,029

SOUND REPRODUCING APPARATUS Original Filed Sept. l5, 1921 2 Sheets-Sheet 2 gnuento'a Patented June 17, 1930 UNITED STATES PATENT oFFIcE HOWARD J'. MURRAY, OIF BROOKLYN, NEW YORK, ASSIGNOR TO It. I. COMPANY, INC.,

4 0F EAST PITTSBURGH, PENNSYLVANIA, A CORPORATION 0F DELAWARE soUNn-lanrnonucme APPARATUS Original application led September l5, 1921, Serial No. 500,938. Divided and this application led Hatch 21, 1927. Serial N0. 178,516.

My invention relates in general to the variation of electric current by means of a light sensitive resistance changing element.

The present application constitutes a division of my co-pending application on electric current affecting device, Serial No. 500,-

` 938, filed September 15th, 1921.

following One of the general objects of my invention is to provide a device which may be used to vary current in an electric circuit in synchronism with the movement of a beam of light.

A further object of my invention is to provide a simple device which may vary current in an electric circuit in desired synchronism with a relative movement of a beam of light or other radiant energy of approximately constant area, color, and intensity.

The application has for additional objects the providing of means including a light sensitive cell designed to be affected by the action of energy radiations of approximately constant amount, intensity, or area. The means in addition permit the radiationsto impinge on the surface of the said element thereby to vary its resistance in accordance with a desired movement of the said radiations.

Still another object of the invention is to provide means for affecting an electric current so as to electrically reproduce and amplify light recorded sound waves, and to also record the said sound waves in the form of light records in combinationwith other light records.

Various other objects and advantages of the invention will be in part obvious from an inspection of the accompanyin drawings and in part will be more fully set orth in the particular description of one form of mechamsm embodying my invention, and

the invention also consists in certainnew and novel features of construction and combination of parts hereinafter set vforth and claimed'.

In the drawings Figure 1 is a plan view of a variable area light sensitive cell.

Figure 2 is a bottom'view of a light sensitive variable area cell composed of a plural- 'strips 17 and 31.

ity of light sensitive resistance changing conductors.

Figure .3 .is a vertical sectional view taken i Figure 7 is a portion of a light sensitive film such as usually employed in connection with motion picture machines but widened to record one or more sound records in addition to theusual photographs.

Figure 8 shows a a light recorded sound record.

Figure 9 .shows a vertical plan and partia-lly sectional view taken through a mechanism containing casing, enclosing a preferred embodiment of the invention mounted on an adjustable support and also means for providing desiredy light and moving sound recor s.`

Figure 10 is a diagrammatic view of the embodiment of the lnvention in a simple plhotophone in combination with a moving m. Y Figure 11 isa plan view of a variable -area device shown in Figure 10.

Figure 12 is a plan view of the ray limiting device shown in Figure 10.

In the following description and in the claims, parts will be identified by 'specific names for convenience of expression, but the are intended to be as generic in their appllcation to similar parts as the art will permit.

Referring to the embodiment of my invention as. partially disclosed in Figures 1 and 2, there is shown -a disc shapedl base of fibre or other insulating material 13. Secured to this base 13 by means of suitable screws 18 `and nuts 28 are two sets of adjustable resistance terminal holding elements consisting of insulating strips 14, yieldable pads 15 preferably made of felt, contact strips .15 preferably made of lead and the terminal holding greatly enlarged view of area, color, intensity,

`Positioned between the contact stri s 15 and 27 is the light affected resistance c anging element 16 preferably in the form of a smooth sheet and consisting) of selenium. This element 16 is positioned y the locating pins 19. The adjustable terminal holding members 17 and 31 are made of. current conducting material of comparatively .high or low resistance as desired due to requirements hereinafter described. It is to be noted that each of the terminal members 17 and 31 have a plurality of circuit connection portions as 20, 22, 23, 24, 25 and 26.

A bracket clamp 29 is oase 13 by means of the screws 32 and firmly secured to the is adjustably secured to the adjusting post 33 by mgl means of a set screw The slots 36 in the base 13 are provided so that the terminal members 17 and 31 of Figure 1 may be rotated about the lower screws 18 as a center.

In operation it will be understood that the cell may be included in an electric circuit by any combination of the connecting portions as 20 and 26 so that current will ow in either direction through the element 16 and from one terminal member to the other. v

The dotted areas as 139 and 140 shown on the surface of the element' 16 (Figure 1) represent portions intercepting light rays. The two portions and the dotted connecting lines may be taken to represent the maximum movement of a beam of light onthe exposed active surface of the element 16.while current is iiowing through same. It is evident that as long as the terminal strips 17 and 31 are of comparatively low resistance and the light remains approximately constant in and position, no appreciable change in resistance of the element 16 will occur. If the light -be caused to move in effect as indicated in Figure 1 no appreciable change in resistance will occur except due to the low resistance of the terminal holders 17 and 31.

However, if one or both of the members 17 and 31 together with the attached parts are rotated from a parallel position in either direction about the lower screws 18 as an axis then the exposed active surface or area of the element 16 can become (say) trapezoidal in form. When the top screws 18 are properly tightened down on the said terminal members 17 and 31 by means of the nuts then suitable contactual relation will be .eected by the terminal members 17 and 31 and the element 16 because of the unyielding .channel form of the said members.

The relatively soft current conducting contact strips 27 .will tend to prevent warping and will be pressed against the surface of the element 16.

Under these conditions it is evident that the total resistance of the element 16 will vary according to the relative position of the light interception by the element, the vform o the active area of the said element, and the combination of circuit connecting portions used to include the element in an electric circuit.-

Such action would cepted laws of computing Yresistance values. '1l`he action may be further described asv fol- OWS I If the light is caused in effect to move over the surface of the element 16 in an imaginary straight line from top to bottom (with refrence to Fig..1) then the current change in the circuit of which the element 16 may bev a portion will of course be changed accordthe terminal member 31 to have a relatively high resistance and the terminal strip 17 to have a relatively low resistance it is evident that the current variation can be affected as desired in magnitude form and frequency. For example if the circuit as shown by Figure 6 includes connecting portion 24: of the high resistance member 31, the said element 16, and connecting portion 23 of the low resistance terminal member 17, and the area of the exposed and active surface of element 16 is that of a trapezoid wider at the top than at the bottom (with reference to Fig. 1) the following action wil occur. As the light beam is moved in effect over the active surface of the element 16 toward the narrow base of the said trapezoidal area the total resistance of the cell as a unit will decrease. As the light is moved towards the wider base the said total resistance will v increase in some Proportion to the movement of the light. I the vrate of movement of light over the active surface of element 16 is increased the rate of charge of'resistance will be accordingly accelerated. 'If theI light which may be of constant intensity is oscillated with the speed of voice or any sound waves as desired thenthe resistance and consequently the curre t in the circuit of which the element 16 may be a portion will be varied according to.the form of the said voice or sound wave.

By employing a light wave of approxif mately constant intensity, color, area, and oscillation period, the current in the circuit of which the element mayr he a ortion may be still further variabl aiiected y further varying the area and t e resistance of the terminal members 17 and 31 and by using different connecting portions of the connecting elements 20 to 26. s

Y' By causing be in accord with ac- If the circuit of which 16 may be a por I tion includes such connecting portions as 16, and 23 and both of the terminal members are of comparatively high resistance then the change of current in the circuit of which the element 16 is a-portion will be at a maximum element 16 vat approximatel\y\ the center or 1n a line connectm zero value and tw1cea-maximum for each the form and the circuit of oscillation of light. Hence frequency of the current in which the element 16 may be a portion may be varied at will according to my invention.

Bychangin the form and area of the element 16 or a p urality of such elements coac tively associated to form in effect a single unit, the specific resistance of the members, the intensity, area and color of the light, 'current variations in form, and frequency may be obtained when the element 16 is a portion of an electric circuit having a source of power, and the light is moved in effect over the exposed surface of the said elements. It is understood that anyl form of radiant energy may be substituted for the light.

The insulating base 13 is held by the clamp 29 as previously described and by moving 29 (clamp) about the support 33 the angle of incidence of the light against the surface of be varied as Well as the the element 16 may relative position of` the said element and therefore the form of the current variation may be additionally changed for any given light oscillation to any desired extent.

By affecting the movement of the said light, its intensity,colo, and area the said form will of course be still further affected.

In Figure 2 we have an embodiment of the invention which employs a plurality of light sensitive resistance changing conductors 37 arranged in. parallel and separatel insulated by positioning same in the mou ded form' 34 preferably made of bak/elite.' This form is provided with holes 35 designed to receive lower screws 18 and is alsoprovided with radial openin s 36 arranged toreceive upper screws 18 o Figure 1.

The element 16 and the pins 19 in Figure 1 may be replaced b the form 34 and conductors 37 of proper imensions to fit over the base 13. Y

When the terminal members 17 and 31 are rotated and 'secured as previously described we again form a trapezoidal area or a rectangular one as desired but'any area will be composed of a plurality of light sensitive conductors 37 in parallel both physically and electrically.

Accepted laws regarding conductance and 'resistance of current conductors disposed in parallel electrically indicate that any change of resistance 1n one or more of the conduc-l as shown in Figure 2 we will affect the total resistance of the circuit of which they may be apart when placed on the said insulating base in Figures 1 and 2 as described above.

f course if the wires 37 were all of the same electrical length and consequently of the same resistance then aHecting any one of the said wires to change its resistance to the same extent would also affect the total resistance'to the same extent but when theare'a is tra ezoidal in form each wire or conductor asa different resistance value than an adjacent one. v

In other words we will have atapering resistance and the movement of the said light in a given direction across the said conductors will vary the resistance of each conductor to approximately the same extent, but will vary the total resistance in proportion to the extent o-f its movement or the number o'f wires or fects.`

The conductors 37 ma be arranged in any desired combination ofy sizes, lengths and specific resistance in order tov secure certain desired results. For example arranged so as to secure a Variation according to the sine law.

In Figure 5 We have a fixed light affected resistance changing cellcomposed of a plurality of having portions moulded into an insulating form 39 preferably of bakelite. The conductors 42 are connected electrically by means of connecting strips. 40 shown in dotted lines and which end in contactual relation with the terminal posts 41 which constitute means for introducing the said cell into `an electric circuit as shown in Figure 6.

Figure 6 consists of a diagrammatic view of an organization of circuit means for varying current by means of the resistance change in conductors 37 in Figure 2.

In Figure 6 these light sensitive wires properly connected are designated as a cell 117 in series with a source of current 118, variable resistance 120, and a winding of transformer 119. The remainder of the organization consists 0f a conventional ampliconductors it afla relative movement 'of the beam of light used in one formof my invention, and I will they may be preferably tellurium conductors 42'.

in either direction vfying set including a vacuum tube havinga also included in one vention.v

It is admitted that causing a reflected beam of light to oscillate due to the vibrations o a diaphragm magnetically actuated or otherwise is old in the art. It is also old to cause the said beam to affect the resistance of a selenium cell or other light affected substances. In addition the art reveals methods of recording the oscillations of a beam of li ht on a moving photographic s urface.

eans for amplifying current variation are also found in the art. .l

MyA invention requires the use of one or more of the above known means more or less improved and arranged to cooperate with the elements shown by Figures 1, 2 and 3 and other means hereinafter described l'for a complete embodiment.- f

In one form of my invention I employ abeam of light and a continuously moving photographic film to tproduce the oscillating light ray as hereinbe ore described. By the use of my invention in connection with one or more of the above known means a improvement is made in the practical and useful recording reproduction and amplification of light and sound records.

When the invention is used in connection with a current amplifier as shown by Figure 6 the device is admirably suitable for use in connection with a talking and moving picture machine and it will be described in connection with such a device, but it will be readily appreciated that the invention is not so limited, but may be utilized wherever an electric current may be alfected to electrically record, reproduce and amplify desired waves yline 109 moving between of light or sound.

Referring to Figure 7, I shows a portion of a lm 68 sufficient in width to include the usual conventional picture space 115 and also additional spaces 109 and 114 designed to receive and record a plurality of light recorded sound records as rline 109 of Figure 8. It is obvious that two or more employed. One film may be emplo ed for the picture records 115 and separate films for the said sound records 109 and 114.

In Figure `8 is shown a magnied'portion 109 of the light recorded sound record as-l sumed to be found in the spaces 109 and 114 of the film shown by Figure 7. The record portion or section of 109 included between the dotted lines 112 of Fi ,re 8 will permit the light to pass through t e lm because of the transparencfyhgf .the light affected portion of the said 68. Hence as the iilm 68 is moved infinitesimal portions of the sinuous the lines 112 will for a given instant permit the light to pass through a given portion. The result in effect' will be a beam of light moving or oscillating great lms may be similar to the said sinuous sound record line 109.

-f this moving beam of to pass be ond the said film 68 and to impinge on t e surface of the said-element 16 f as shown 1n Figure 1 or conductors 37 as 2 and previously described,

shown in Figure then the sound or energy waves represented by the sinuous line 109 in Figure 8 will be electrically reproduced in proper synchronism and amp cdas desired as shown in Figure 6.

In Figure 9 there is shown a mechanism containing casing 43' provided with an air tight cover (not shown) fastened to the said casing by-suitable screws which fit into the drillings 44. This casing contains a support rod 46 having a heavy slidable base 45. Mounted on the said rod 46 is a second smaller casing 49 designed to resist pressure both inside and out and adjustably supported to the said rod 46 by means of a set screw 47 and a clamp 48 attached to the casing 49. An air tight cover (not shown) closes 49 and is fastened to same by means of bolts passin through the openin s 50. Openings 51 an 55 are designed to a it gas, air, etc. into the said casing or remove same -by means of the pipes 58 and 62, valves 53 and 56, and handwheels 54 and 57. These opemngs may also be used to create a vacuum formed by the enclosure of the casing 49. A system of circulating pipes 102 are designed to bring heated or cooled-'liquid or gas to the interior of the casing 40 and thereby raise or lower the temperature of its interior and any elements positioned therein. Adjustably mounted on adjusting post 33 is a-light affected resistance changin cell as shown in one embodiment of my invention by Figures 1, 2 or 5. The post 33 is in turn ad'ustably secured to the horizontal rod 62 by t e sliding clamp of post 33. The rod is further. securely fastened to projections of thecasing 49 by means of set screws 61. f The cell is suitably connected to an external circuit of which it may be a portion by means of the insulated conductors 64 and insulatedy terminals 63 passing through the walls of the casing 49 so as to make same airtight under pressure or vacuum.

A. suitable lens 65 is desirably in a desirable opening of the casing 49 so as to prevent cracking 01 ressure of the bolted element 66 .which Also contained in the interior o closure formed by the enexposed and develo by Figure 7 proper light is permitted positioned Y sol s the said lens 65 in its desired osition.

the .mechanism casing 43 v is a portlon or all of a movable previously" CFI ably connected to insulated terminals 78 'and by means of rotatable an external source of power. The supporting post 74 may be rotated in the seat formed in the flange 75.

and projecting from the support ears designed to position the shafts 107 These shafts107 have Integral with casing 49 are two properly support and shown in Figure 111. win ed projections 67 handles 106. The shafts 107 are formed about tight fitting pins turning in the openings of the ears 81 yof Figure 9 so as to be stationary except when moved by the adjusting handles 106 or by other suitable means. Due to these area varying elements the space as indicated by dotted lines 112 on Figure 8 and included between the dotted lines may be varied as required by rotating the shafts 107 by the handles 106. It should be noted that the dottedlines 112 are really the edges 112 of theelement 67 shown in Figure 11.A Rays portions 105 are designed to cause the film 68 to move smoothly and closely over the elements 67 and to permit ne adjustment due the material used.

Adjustable clamp) 83 attached to and supported by rod 74 y means 'of a set screw in turn adjustably positions clamp 86 which supports the light limiting members 80 by means of bracket 135 as shown on Figure' 12. The slots 113 permit the movable members 80 tobe moved relative to each other in order to vary the width of the space 116 formed by such movement. preferablydesigned to be yieldable due to the curved portion 137 `and the said portion vmay be formed soV as to give suitable pressure against the film 68. l

Also adjustably supported by supporting rod 74 is lens rod 84 in turn adjustably supiilm porting clamped members 87 and 88 ending in lens holders 108 in which are suitably mounted condenser lenses 89. A third support rod 91 also secured to the casing 43 by means of Hoor flange 90 and suitable bolts is used for supporting the source of light 95, reflector 96, socket 94, and socket clamp 92 attached to adjusting rod 93 by a set screw.

Openings having insulating'bushings 110 admit current conductors 97 and 98 which supply a variable current to the filament of belt 73, and power` wheel fi and manually movable to the possible thinness of The members 80 areI It is assumed that the film 68 may be a porin a conventional motion but designed to receive a lm similar to that shown on Figure 7 or tion of film used picture machine perhaps twoseparate films as hereinbefore mentioned. In Asuch an event two or more sets of pulleys 104 may be used to guide the m 68 in or out of the casing 43. v The operation of the elements shown on igure 9 may be described as follows: Desired light is produced by passing cur- The opening 112 formed by the space between the e' ges of the variable aperture member 67 shown on Figure 11 may e considered at right angles to the adjustable opening 116 between the ligh t limiting members 80 of Figure 112. Hence if the lilm 68 was removed the light would be permitted to pass through the rectangular opening formed by the two-said spaces overlapping each other. But in operation the fi 68 is moving between the said members 80 and 67 and only the light al'ected soun-'d record portion as ure 8 will permit light to pass. through the said film 68. ne dimension is fixed by the opening and the other dimension will vary with the width of the said film record 109. Assuming that the record 109 of Figure 8 may be represented for the sake .of description by a sinuous line of approximately constant width it is evident that the transparent portion included in the said area will in effect reciprocate at right angles to the direction of movement of the said-film 68.

It is of course obvious that the record need not be of when properly 109 of Fig-- constant width and that the transparent portlon may increase in both directions at right angles to the motion of the 68. l In this case the amount of'light falling on the elements 16 of Figures 1, 2 and 5 would not be of constant amount. But it is evi'dent that the form of the element could be so arranged that the. current variation of the circuit of which the elements 16 may be a portion would be a faithful reproduction of the light record.

It is also evident that theA portion of li ht passing through the said transparent portion 109 of lm 68 due to the said reciprocation -in effect of the transparent portion will in effect become a light passing on of impingin l passing a 4 in. converge and o the light aifected resistance changing eleaudible sound waves in sync lsimilar oscillating beam of to lens 65 in divergin lines.

The lens 65 is assumed to be of suc smtable formas to cause the light rays 103 to impinge on the surface ment 16 as shown on Figures 1, and 5, and hereinbefoie described as according to my 1n- By adjusting the relative positions of condenser lenses 89 it is apparent that the point of focus may be varied with respect to the surface of the ilm 68.

In addition the adjusting means 33 suportin the cell-` will allow movement relative to the ens65 and thereby vary the intensity and area of the light rays 103 at the instant of the sai -'light rays on its acn some operations it will be possible to eliminatethe lens 65 and permit the light rays 103 to strike thecell directly after through the film 68. By rotating the cell in a horizontal lane about the supportin post 33 'the lig mitted to impinge on the surface of the elements 16 at an angle. By emiloying all the adjusting means hereinbefore tive area.

escribed many 'variations of the effect of the light o n the said surface of the elements 16 ma be obtained. Hence the resistance of the lig t aifected element 16 may be varied and the current of the circuit of which it may be a ortion also varied and these variations amplified as indicated by the diagrammatic connections as Shown by Figure 6. In addition this variaf tion may be eected faithfully in synchronism with the moving sound recorded on a moving film-68, and by means of a suitable receiver 125 re roduced `into ronism with picture records relatively positioned on the said film v 68.

to the ori words the `original sound waves may Due Ito the adjustin means herein described the amplitude, requency, pitch and therefore overtones and harmonics of the audible vibrations roduced by the said receiver 125 may be pro uced and varied' relative to the sound waves recorded on the. sound `record 109 on the said moving In other l be reproduced by the receiver 125 so distorted that they'- may be unrecognizable, or distorted records 109 on the said movin film 68 may be so corrected by the hereinbe ore described adjustments and 'nal sound waves. In other words we may rst record the true waves so as to be distorted and then correct same so as to be reproduced in the receiver 125 as faithful reroductions of the' original sound waves.

Figure 10 indicates a diagrammatic' assembly 'of the elements required for am lifying current waves byan embodiment ofmy inre 5. It ,also lindig sound records on vention as shown in Fi cates a method of reco 131 t rough t rays 103 may be perthe sai diaphragm records 109 vas variations as to be similarance, voltage regulator,

- any a movable film. as 68. A source of light 126 is suitably placed `in a reiiecting enclosure 136 so formed as to emit a beam of light 128. A lens 127 is em loyed to concentrate the beam on a prefera ly hinged diaphragm 129 actuated preferably by a suitable magnetic core in turn actuated by Winding 130, but of course, the said Idiaphragm 129 may bevibrated or actuated by any means. .The said beam'128 is therefore reflected by the reiiecting armature or diaphra 129 as an oscillating beam of light lens 132. The ens 132 may be arranged to change the color of the moving beam 131 and focus it on the moving li ht wave recording' means 142. When suitably enclosed as shown and described inFi re 9 this record or so called iilm 142 will be aielcted b the movement of the said beam 131 to indicate its oscillatingnmovement thereby when suitably treated as own in the art. l Or the record receiving film 142 may be removed and a light affected resistance changing element 133 more specifically shown by Figure 1 may be positioned in the path of the said oscillating beam 131. It is understood that the light affected element 133 forms a portion of an electric circuit as shown -by Fi u re 6. By changing the form of the said e ement 133 the current in the circuit of which 133may be a portion may be aifected variabl with reference to the movement of 129 'and hence the current in the Windlngs 130. In other words the current in the circuit'of which 133 is av portion, (as in Figure 6) may be decreased as the cur# rent in .winding 130 increases, or any instantaneous relation between in the winding 130vand the element 133 may be obtained by suitable design and adjustment according to my inventlon. It should ceivedthat the variation of the record from the true light oscillation may be rectified by a suitable desi -of the element 133. It is also to be note that the {ilm 68 as shown in Figure 9 may have been previously used as the film 142 to record the record being used to affect the cell shown in Figure 9.

This embodiment of my invention is shown and described merely to indicate one of the many possible applications of my invention. It is evident that y proper design the cell including an element 16 may be employed in organizations constituting-such devices as an oscillator, rectifier, detector, relay., a photo electric condenser, a photo .electrlc impedampliier, and in fact device depending on the variation of current for its proper action.

While I have shown and described and have pointed out in the annexed claims certain novel features of my invention it will be understood that various changes in the form other desired the current changes .taching the device to a and details of the device illustrated, such as providing means for multiplying a number of elements 16 in co-operative arrangements may be made.

It is also evident that there are many ways of combining the talking and moving picture records in the same film or in separate films to properly work along the lines of conventional moving picture apparatus.

It should be further evident that a plurality of light sources as 95, 'means for atmoving picture machine providin elements with curved surfaces, etcfcoul have been shown.

It should be still further obvious .that various other changes, omissions and substitultions in the particular form of invention illustrated and in its operation may be made 'by those skilled in the art without departing from the spirit of my invention.

Having thus described my invention I 'claim 1. In a device of the class described, a light source of constant intensity, means to select a light beam` of constant area of cross section from said source, a lightsensitive member comprising a plurality of electrical paths, each of a dierent resistance when illuminated by said constant beam, and means to cause said constant beam to act successively upon successiveones of said paths whereby to determine the resistance of said light-sensitive cell according to the paths selected.

2. In a-device 4of the class described, ali ht source of constant intensity, means to se ect a light beam of constant area of lcross-sectionfrom, said source, a sensitive member respond-v ing in electrical resistance according to the illumination thereon and comprising a plurality of electrical paths which each has a different resistance from that of the other paths when illuminated by said constant beam, and means to cause said beam to impinge on a selected path whereby to determine the electrical resistance' across said member.

3. In a device of the class described, means for producing a light beam of constant quantity, a light-sensitive member responding by electrical resistance when illuminated and comprising a plurality of electrical paths, each responding by a different electrical resistance when illuminated by said beam, means to cause said constant beam to impinge upon a selected one of said paths so that the light-sensitive member will vary correspondingly in its total resistance, and means to adjust the ratios of the relative resistances of said paths.

4. In a device of the class described, a light source of constant intensity, a light-sensitive member comprising a plurality of electrical paths which ea'ch dier in electrical resistance and are connected electrically in multiple, a lm bein for its major-portion' opaque and having a light-transmittingzig-zaglinetherefilm so that the light from said source is transmitted through said zig-zag track and said slot to said sensitive member and encounters the one of said paths determined by the point of intersection of said zig-zag track with said slot, whereby the total resistance across said cell 1s determined by the response of said selected path to the illumination..V

5. I I n a device of the class described, a lightsensltlve. member comprising a, plurality of substantially parallel electrical paths connected electrically in multiple and each diffel-lng 1n electrical resistance in response to a constanlfI quantity of light, a lm having an o of with a zlg-zagy light-transmitting track thereon, a source of light of constant intensity, a light-obscuring shutter member located between said source and said light-sensitive member, and having a slot therein extending substantially parallel to the direction of said paths, and means for passing said film when opposite said light-sensitive member in a direction perpendicular to the direction of said light paths, so that said slot and track acting 1n' conjunction permit the passage of a single light beam of constant quantity from said source to a portion of said light-sensitivev member selected by the point of intersection of said slot and path.

, 6.v In a device of the class described the combination of a mechanism containing casing having openings for the passage of air, gases', liquids, and electric conductors, and designed to exclude light, means contained in the said casing comprising a source of' paque portion lengthwise therearranged so as to concentrate portions of the salild light on desired portions of the said ce 7. In a device of the class described, the combination of a plurality of light ai'ected conductors having different normal resistance values, means for adjustably varying the efective resistance of said conductors in desired progression and at a desired rate, and placing same in a circuit in parallel electri-l cally, and means for maintaining the above said means in a suitable gas and admitting an oscillating beam of light of approximately constant intensity to the said effective portions of the said conductors.

8. A photophone comprising a light susceptible resistance-changing element having predetermined diiering resistances when,l

light of approximately constant intensity and area falls upon different predetermined portions thereof, means or'producing light of constant intensity, a Iilm having a light recorded sound wave record thereon comprisingl a light-transparent strip of uni orm width but varying position along the length of the film, and means cooperating with said film to causeva beam of constant area from said source to fall upon portions of said element determined by the respective positions of the sound wave record on said lilm.

9. In a device of the class described, the

combination of a light affected resistance 'changin cell having a resistance portion, a

light a ected resistance changing portlon comprising aplurality of light aiiectedv conductors o various lengths and resistance values arranged electrically in parallel, a second resistance portion, means for introducing the above named portions in an electric circuit organization, and means to lproduce a beamof li ht of approximately constant intensity an area while excluding all other light, and to cause a change of position of said beam `whereby to aiect a predetermined one of said conductors according to the position of the light.

10..In a device of the class described, `the combination o two resistance portions constitutin contact members and holders, a

' light a ected portion consisting of a plu# rality of light sensitive conductors, means for adjusting the said holders so as to vsecure the said conductors whereby they may be introduced into an electric circuit in arallel electrically, and their respective resistances varied, a pressure resisting container sur. rounding said holders and conductors, and means to produce a beam of light of approximately constant intensity and area and to cause said beam to be projected upon successivelyr predetermined conductors wheilluy to vary the totalresistance across said 11. In a device of the class described, the

l combination of a light susceptible cell com- -varies in a desired posed of a plurality of conductors connected electrically inI parallel and arranged so that the resistance of the successive conductors varies in a desired progression, `means for producing a beam of light ofV approximately constant intensity and area and causing the beam to be projected upon the said conductors,I and means to move said beam relative to said conductors whereby to vary to total resistance in proportion to said movements.

12. In a device of the class described, the

combination of a light susceptible cell composed of a plurality of conductors connected electrically in parallel and arranged so that the resistance of the successive conductors progression, means for producing a beam of light of approximately constant intensity and area and causing the 

